Tube wizards - can I mix brands of KT88s ina a quad set?

[nickbaba]

O most knowledgeable tube wizards - can you tell me, is it OK to mix different brands of power tubes in one amp? Is it more important that the tubes test similar?

I have a tube amp that takes a quad of KT88s. I've been slowly collecting old GEC KT88s off ebay, a mixed bag to be sure. In one recent sale I got a pair of NOS Genalex Gold Lions, which I'd like to use, but I only have a pair of them. (They are originals, not the current re-issues)

Is there any reason I shouldn't mix them with a pair of decent vintage GEC KT88s? I've heard that they are essentially the same tubes, and that the (original) GLs were basically re-branded to appeal more to consumers.

As long as the tubes test as same/similar, and the amp is properly re-biased, should it be fine to mix them as a quad set? Or am I going to run into problems?

[Ali Tait]

It will work fine as long as they are reasonably matched and the amp is biased correctly.

How it will sound may be another matter.

[nickbaba]

Well, that's part of my question... will it affect the sound?

[Ali Tait]

Try it and see. Different makes do tend to sound different.

[Arkless Electronics]

VALVES man VALVES!! We're not the 51st state yet...

[nickbaba]

The question is, if I mix valves will it sound better than mixing tubes? ;)

[Radford Revival]

It will work fine. I'd imagine (but have not attempted to prove this) that mixing and matching valves of very different construction / completely different brands may result in slightly worse distortion due to poorer cancellation of each valve's inherent transfer curves.

For example some brands implement EL34s as beam tetrodes and some as pure pentodes, the resulting differences if used each in a push pull pair may not work as well, in terms of distortion, as both the same of either.

[anthonyTD]

Hi Nick,
If they are genuine old stock Genalex, then they are electricaly the same as old stock GEC Tripple Getters, the obvious main physical diffrence is; the Genalex may have black base wafers, where as the GEC mostly had Brown,[diffrent shades accross the era's too] as others have said, its important that they have similar test figures, and that they are biased correctly.
Hope this helps.
O most knowledgeable tube wizards - can you tell me, is it OK to mix different brands of power tubes in one amp? Is it more important that the tubes test similar?

I have a tube amp that takes a quad of KT88s. I've been slowly collecting old GEC KT88s off ebay, a mixed bag to be sure. In one recent sale I got a pair of NOS Genalex Gold Lions, which I'd like to use, but I only have a pair of them. (They are originals, not the current re-issues)

Is there any reason I shouldn't mix them with a pair of decent vintage GEC KT88s? I've heard that they are essentially the same tubes, and that the (original) GLs were basically re-branded to appeal more to consumers.

As long as the tubes test as same/similar, and the amp is properly re-biased, should it be fine to mix them as a quad set? Or am I going to run into problems?

[HanTheMan]

Generally unmatched output tubes are sometimes used by musicians to get a particular sound, may not work as well for hifi when you want to reproduce sound rather than create it. As long as the amp is properly biased it will work electrically, if you have test equipment you can try to see if they match (KT88 and other octal based teseters are fairly common and you can get automatic testers these days). No one can really tell you how they will sound unless you try yourself in your amp :).